Silicon-containing lubricant additives



United States Patent Oifice 3,192,164 Patented June 29, 1965 3,192,164 SILICON-CONTAINING LUBRICANT ADDITIVES Edwin L. De Young, Milwaukee, Wis., and Roger W.

Watson, Highland, Ind., assignors to Standard Oil Company, Chicago, ill., a corporation of Indiana No Drawing. Filed Jan. 16, 1962, Ser. No. 167,220 2 Claims. (Cl. 252.49.6)

This invention relates to certain ketones for inhibiting the tendency of hydrocarbon lubricant oils to cause excessive wear of silver and silver-containing bearings.

Many hydrocarbon lubricant oils contain sulfur compounds as oxidation or corrosion inhibitors. These sulfur compounds however promote excessive wear in silver and silver-containing bearings and bushings.

It is an object of the present invention to provide an additive for use in such lubricant compositions which tends to substantially inhibit excessive silver wear.

Briefly, in accordance with the invention, it has now been discovered that the reaction product of a ketone with silicon disulfide is an outstanding anti-silver wear additive when incorporated into hydrocarbon oils tending to cause excessive wear.

The present additives may be prepared simply by reacting the corresponding ketone, which is preferably a dialkyl ketone having from 1 to 20 carbon atoms in each alkyl group, with silicon disulfide under anhydrous conditions, and preferably at a temperature of about, say, 8-0-150 C., for sufficient time until hydrogen sulfide evolution ceases. The structural formula of the resultant product is not presently known, nor is it readily ascert'ainable. However, it has been definitely established that a reaction product having characteristics different from either reactant is obtained. Thus the preparation of the herein-described additives follows the technique of Fremy, Ann. Chim. Phys. (3), 38, 314 (1852), notwithstanding the statement by Malatesta, Gazz. Chim. Ital., 78, 753-63 (1948); Chemical Abstracts, 43, 4630 (1949), to the effect that SiS (does not) react with esters or ketones contrary to Fremy.

It has been discovered, in further accordance with the invention, that the present additives are outstanding with respect to imparting oxidation inhibition to lubricants containing them. Thus, not only is it possible to utilize the silver wear-inhibiting properties of the present additives to reduce the wear promotion of sulfur-containing oxidation inhibitors, but the amount of such oxidation inhibitors may likewise be reduced inasmuch as the present additives are themselves inhibitors against oxidation.

It appears that a wide variety of ketones may be employed herewith, although the dialkyl ketones, in which each alkyl group has from 1 to '20 carbon atoms, offering advantages With respect to ease of preparation, solubility, and effectiveness in inhibiting silver wear and oxidation. Examples of suitable dialkyl ketones include acetone, methyl n-propyl ketone, methyl isopropylene ketone, diethyl ketone, hexanone-Z, hexanone-3, methyl n-octyl ketone, etc. -Polyketones, including acetylacetone and acetonylacetone; unsaturated ketones such as mesityl oxide and phorone; halogenated ketones such as bromoacetone and chloroacetone; cyclic ketones such as diphenyl ketone and dinaphthyl ketones, may also be used, either alone or in admixture with each other.

Lubricant compositions which advantageously may be incorporated with the present additive are the hydrocarbon oils of suitable viscosity range, and which may contain various additives for different purposes. The hydrocarbon base may be either a natural or synthetic (e.g., propylene or isobutylene polymer) oil, suitably having a viscosity from about 20 S.S.U. at 100 to about 3,000 S.S.U. at 210. Additives commonly employed include detergents such as the metal sulfonates or metal phenyl sulfides; oxidation and bearing corrosion inhibitors such as the metal dithiophosphates or the phosphorus pentasulfide pentene reaction products or the sulf-urized hydrocarbons; viscosity index improvers such as the polysiobutylenes; and pour point depressants of various types. Ordinarily, silver Wear is fostered by the presence of sulfur compounds, generally from an organic compound, as exemplified by any of the foregoing sulfur-containing compounds, -or by various other materials such as octyl polysulfide, sulfochlorinated olefins, or sulfurized sperm or tall oils, etc. With these formulations, inclusion of the present silver wear inhibitors in amounts ranging from as little as 0.05 percent to about 3 percent or even more, depending upon the intrinsic wear tendencies of the lubricant and on the degree of improvement desired, will ordinarily suffice to provide sufficient inhibition against undue silver wear.

As indicated earlier, the present additives may be prepared simply be reacting silicon disulfide with a ketone under anhydrous conditions. The temperature is advantageously around C., plus or minus about 50 C. and the reaction is advantageously conducted for sulficient time to permit substantially all of the hydrogen sulfide evolution to cease. Under some circumstances it is advisable to conduct the reaction in the presence of an inert solvent, that is, a normally liquid material which is inert with respect to the reactants and which does not deleteriously affect product quality.

To illustrate and exemplify the present invention, the following examples are submitted. It is to be recognized that they are illustrative only, and are not to be considered wholly definitive with respect to scope or conditions.

Example 1 This example illustrates the preparation of the reaction product of silicon disulfide with methyl-n-heptyl ketone.

To a glass flask containing 14.2 grams (0.1 mol) of methyl-n-heptyl ketone is added 9.2 grams (0.1 mol) of finely powdered silicon disulfide. The mixture is heated with stirring at 100-110" C. for five hours until hydrogen sulfide is no longer evolved.

The hot mixture is filtered and the filtrate evaporated under vacuum to remove unreacted starting material. The resultant product is liquid at room temperature, and contains 0.10 weight percent silicon.

To test its efficacy for inhibiting excessive silver bearing wear, tests are conducted with the Falex tester (J our. Inst. Pet., 3-2, April 1946), utilizing a silver ball on steel wear surfaces. The control consists of a 73 viscosity index mineral lubricant base, containing 2.8 percent detergent (barium neutralized and hydrolyzed reaction product of phosphorus pentasulfide and a hydrocarbon), 1.0 weight percent calcium phenate and 0.2 percent sulfurized terpene. Under the conditions of the Falex test, the silver ball exhibits a weight loss of 275 milligrams.

By contrast, when the same lubricant composition is inhibited with only 0.5 weight percent of the above-described additive, the weight loss strikingly drops to 72.1 and 77.1 milligrams in duplicate tests.

The additive is also tested for oxidation inhibition under the conditions of the Stirring Sand Corrosion Test (S.S. C.T.). For this test, a copper-lead test specimen is likely abraded with steel wool, washed with naphtha, dried and weighed to the nearest milligram. The cleaned copperlead test specimen is suspended in a steel beaker, cleaned with a hot tri-sodium phosphate solution, rinsed with Water, acetone, and dried, and 250 grams of the oil to be tested, together with 0.625 gram lead oxide and 50 grams of a 30-35 mesh sand charged to the beaker. The beaker is then placed on a bath or heating block and heated to a temperature of 300 F. (plus or minus 2 F.) while the contents are stirred by means of a stirrer rotating at 750 rpm. The contents of the beaker are maintained at this 3 temperature for 24 hours, after which the copper-lead test specimen is removed, rinsed with naphtha, dried and weighed.

The test specimen is then replaced in the beaker and an additional 0.375 gram of lead oxide added to the test oil. At the end of an additional 24 hours of test operation the test specimen is again removed, rinsed and dried as before, and weighed. The test specimen is again placed in the beaker together with an additional 0.250 gram of lead oxide and the test continued for another 24 hours (72 hours total).

The loss in weight of the test specimen is recorded after each weighing. A weight loss of 200 mg. or less in 48 hours, and 500 mg. or less in 72 hours in allowable.

Utilizing a commercial heavy-duty S.A.E. 30 motor oil base and testing at 48 and at 72 hours, the respective weight losses when only 0.5 weight percent of the abovedescribed additive is employed, are 260.9 and 271.6.

Example 2 Example 1 is repeated except that equal molar quantities of diphenyl ketone are employed. Again, excellent performance under the silver Falex test and in the S.S.C.T. are observed.

Example 3 Example 1 is repeated, but with an equivalent quantity of methyl dodecyl ketone, and with methyl octadecyl ketone. In each instance excellent results are observed under the silver Falex test and the S.S.C.T.

Example 4 hydrocarbon group attached to the carbonyl group. While the di'alkyl ketones are to be preferred, it is evident that the aryl, alkaryl, and even unsaturated ketones may likewise be employed, provided only that the additive has sufiicient solubility in the lubricant oil in question so as to afford adequate silver Wear inhibition.

From the foregoing description it is manifest that there has been provided in accordance with the invention an outstanding additive for reducing, or inhibiting excessive silver wear characteristics of hydrocarbon lubricant oils normally tending to demonstrate excessive silver wear. While the invention has been described in conjunction with certain specific embodiments thereof, it will be appreciated that these are by way of illustration only, and that numerous alternatives, modifications, and variations will be evident to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall Within the spirit and broad scope of the appended claims.

We claim:

1. A hydrocarbon lubricant composition normally tending to cause excessive silver Wear and containing, in a minor amount sufficient to inhibit such wear, the oil soluble reaction product of silicon disulfide with a dialkyl ketone wherein each alkyl group contains from 1 to about 20 carbon atoms said reaction being carried out under anhydrous conditions at a temperature in the range of about to about C.

2. Composition of claim 1 wherein said ketone is methyl-n-heptyl ketone.

References Cited by the Examiner UNITED STATES PATENTS 2,588,083 3/52 Burkhard et a1 260448.2

DANIEL E. WYMAN, Primary Examiner.

ALPHONSO D. SULLIVAN, Examiner. 

1. A HYDROCARBON LUBRICANT COMPOSITION NORMALLY TENDING TO CAUSE EXCESSIVE SILVER WEAR AND CONTAINING, IN A MINOR AMOUNT SUFFICIENT TO INHIBIT SUCH WEAR, THE OIL SOLUBLE REACTION PRODUCT OF SILICON DISULFIDE WITH A DIALKYL KETONE WHEREIN EACH ALKYL GROUP CONTAINS FROM 1 TO ABOUT 20 CARBON ATOMS SAID REACTION BEING CARRIED OUT UNDER ANHYDROUS CONDITIONS AT A TEMPERATURE IN THE RANGE OF ABOUT 50 TO ABOUT 150*C. 